Since polycarbonate resins are excellent in mechanical strength, heat resistance, transparency or the like, the resins are widely used in fields of materials of electronic/electric/OA equipments, automobile parts, construction materials, medical appliances, sundry articles or the like. However, since polycarbonate resins has a high surface resistance value, it is difficult to eliminate the static charge generated by contact and friction. Therefore, polycarbonate resins have such problems that waste and dust are attached on the surface of molded product to deteriorate the appearance and transparency, electric shock causes discomfort of human body, noise generates and improper operating signals for a machine are produced. From these, it is demanded to provide a polycarbonate resin composition and molding products formed by melt-molding the said resin composition which have antistatic property by reducing the surface resistance value of polycarbonate resin without deterioration of polycarbonate resin properties in nature.
Generally, as the polycarbonate resin composition having antistatic property, there has been proposed a resin composition comprising polycarbonate resin, phosphonium sulfonate, phosphite and caprolactone-based polymer which are blended (refer to Japanese Patent Application Laid-open (KOKAI) No. H09-194711). However, the said resin composition has such problems that fluidity variation is large so that stable molding is difficult, yellow or brown coloring generates during the melt-kneading step and molding step, and the mechanical strength and antistatic property are deteriorated. It is thought that these problems are caused by high melt viscosity of polycarbonate resin so that the melt-kneading temperature and melt-molding temperature rise and the thermal decomposition of resin notably generates.
There have been also proposed a polycarbonate resin molded product for optical use comprising a polycarbonate resin and 1 to 60% by weight of polycarbonate oligomer blended (refer to Japanese Patent Application Laid-open (KOKAI) No. S61-123658), and a resin comprising a polycarbonate resin and 10% by weight or more of polycarbonate oligomer having a molecular weight of 2000 to 5000 (refer to Japanese Patent Application Laid-open (KOKAI) No. H09-208684). However, these proposals only suggest that the fluidity is affected by blending oligomer when using the molding products for optical arts.
In the above prior arts, when the fluidity of resin composition having antistatic property is improved, the color hue and mechanical strengths tend to deteriorate notably. Therefore, it is desired to provide an antistatic polycarbonate resin composition and molded product formed by melt-molding the said resin composition, which resin composition has totally well balanced excellent properties including heat resistance, in which yellow- or brown-coloring can be prevented even though under melt-kneading step, molding step and such a circumstance that it is used at high temperature for long times, and the fluidity is improved without notably deterioration of mechanical strengths and transparency.